STUSB4500 PDO profile doesn't change after setting.

BHan.1 · ‎2021-03-08

Hi,

Through some setup, I was able to access STUSB4500 using the GUI tool in STSW-STUSB002.

After I set the second profile to 20V/5A, I connected a power supply with 5V/3A and 20V/3.25A PDO capability. But nothing changes and the voltage is unchanged at 5V.

Is there any problem with my current configuration? I attached all the images from the GUI and my Schematics.

There are 2 problems.

1. As I mentioned above, the voltage doesn't change and only 5V is detected.

2. I used DMP3018SFV Pch MOSFET, which is a direct replacement of STL6P3LLH6 MOSFET used in the STREF-scs001v1 board.

When I measure the voltage between the pi filter inductor and the MOSFET, 500mV~2.8V is measured.

Benoit FORET · ‎2021-03-09

Hi BHan1.

Yes. For PDO2 @ 20V, current must be set as the minimum required for your application (1A or 2A maybe?). When set as 5A, the IC understands the power supply is not powerful enough (only 3.25A max current) to power your application, so moves to a lower priority PDO or 5V Default PDO. Then you can play with REQ_SRC_CURRENT parameter: if you disable it, the IC requests to the power supply the current defined by you in PDO2 (so your MIN). If you enable it, the IC books the max current proposed by the power supply (so in this case 3.25A, but it can be less or more depending on power supplies capabilities.

More details about it p.11 and 12 from the datasheet

rgds

BHan.1 · ‎2021-03-10

Hi Benoit,

Thanks for the clarification, I misunderstood the document and I thought when I set the current to the highest level, STUSB4500 will automatically detect and pull the most current from the available source not exceeding the set current(For my case, 5A).

So I changed the current setting like below, but I'm facing another problem. Now the power supply jumps between 5V and 1.3V and I'm able to hear a little click sound as it jumps from one voltage to another.

I added the video as attachment.

I'm using a power supply with 5V/3A and 20V/3.25A and the switch circuit is same as the STREF-scs001v1 board.

I just replaced the IC because I didn't know how to recover the IC from flickering. But I'm not sure what I did wrong to make this happen.

Do you have any recommended settings for PD adapter that will give 20V input with max current that the power supply is able to supply?

Best regards

Brian

Benoit FORET · ‎2021-03-11

Hi Brian,

the connection / disconnection cycle you see is likely due to the inrush current causing a temporary voltage drop on VBUS that is understood by the controller as a voltage mismatch from the SOURCE, therefore opening VBUS switch, reinitiating connection etc.. etc...

Because USB-C is cold socket, one must prevent from big inrush current at connection time, when the MOS is closing. If the input capacitor of the load, your system, is too high, maybe you can add a inrush current limiter or a switch with soft/start feature. A good practice is also to sink few current at the beginning and to increase sequentially, also for preventing to SINK more than the SOURCE can provide and avoid collapsing it. In case you can play with this with you battery charger or power managment IC, it is better.

Last comment is to enlarge the OVP/UVP threshold from 5% to 20% in the GUI, in order to be more tolerant to this kind of phenomena.

It should not be an issue in this case, but having 2 PDOs at the same voltage value is not authorised by the standard (PDO2 and 3 @ 20V).

Hope it helps,

Rgds,

Benoit